Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 231935
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
335 PM EDT Mon Apr 23 2018

.DISCUSSION...

A mild day across southeast Michigan, as temperatures top out around
70 degrees. Unfortunately, going to be shaving close to 10 degrees
Tomorrow, and close to another 10 degrees on Wednesday.

Large upper level low over the central Mississippi River Valley this
afternoon will slowly slide east into the Central Appalachians
Tomorrow night, and begin to merge with the northern stream upper
level wave currently tracking through Central Canada.

Modest height falls and enough moisture transport expected tonight
(PW Values rising to near 1 inch) into Tuesday to support light
showers with low level troughing/inverted surface trough becoming
established, along with some modest mid level fgen/upper level
divergence. Although the forecast will feature showers likely, good
chance the bulk of daylight hours will be dry at any given point.

Stronger upper wave/height falls to arrive Wednesday morning, with
the mid level cold pool (-25 C at 500 MB) tracking across the
Central Great Lakes during the day. Deeper moisture looks to be
shunted off to the East Tuesday night, so may be able to get away
with most of Wednesday being dry, as the 12z NAM/GFS remain more
progressive with the northern stream trough axis. However, the 12z
Euro is remaining consistent with a slower/closing off 700-500 MB
low developing over southern Lower Michigan, and with support from
UKMET, prefer to keep a chance of showers in the forecast for
Wednesday. Temperatures should be holding in the lower 50s as 850 mb
mb temps lower to between -2 C to zero.

Although the Euro even wants to hold onto showers Wednesday evening,
will allow for the post frontal drying/subsidence to kick in, with
skies clearing out Wednesday night as anticyclone builds in.
Assuming this is a case, good chance for many sites to drop at or
below freezing with favorable radiating conditions.

Fairly quiet weather for the latter half of the week into the
weekend. A shortwave ridge will slide through the region on Thursday
resulting in another sunny day with temps reaching into the 60s as
southwest flow returns ahead of the next trough. This trough will
sweep through lower MI on Friday bringing a narrow band of showers
across the area along a cold front. Surface high pressure quickly
filling in behind this front with upper level ridge building east
into the region as well. Northwesterly flow will prevent better
heating across the Great Lakes but temps will still hover in the mid
50s through the weekend.

&&

.MARINE...

The ridge of high pressure over Lake Huron will slowly exit to the
east while moisture moves in from the south overnight via the
Tennessee Valley low pressure system. Scattered rain showers will
persist over the area Tuesday into Wednesday. A weak cold front
moving in early on Wednesday will shift light and variable winds to
moderate and northerly with gusts above 25 kt by midday. This will
result in wave heights likely above 4 ft and therefore above the
threshold for Small Craft Advisories. Winds will weaken Wednesday
evening and back to westerly then southwesterly by Thursday evening
as high pressure slides through the Great Lakes. The next cold front
is still on track to arrive Thursday night into Friday.

&&

.PREV DISCUSSION...
Issued at 103 PM EDT Mon Apr 23 2018

AVIATION...

High clouds streaming in from the low pressure system over the lower
Ohio Valley remain the only item of note through the afternoon and
evening as the ridge of high pressure over the northern Great Lakes
continues to move off to the east. Ceilings will gradually lower
through the evening and scattered light rain showers will move in
from south to north overnight as moisture eventually saturates the
dry column. Scattered showers will continue through the remainder of
the period and result in MVFR conditions after sunrise. Light
southeasterly winds will prevail through the period.

For DTW...Benign weather through the evening. Scattered light rain
showers expected to move in from the south after 07z tomorrow
morning, allowing MVFR conditions to develop before sunrise and
persist through the afternoon.

DTW THRESHOLD PROBABILITIES...

* High for ceilings aob 5000 ft after 08z Tuesday.

* High for rain as precipitation type.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

DISCUSSION...SF/DK
MARINE.......TF
AVIATION.....TF


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